Mozhgan Mahdizadeh Rokhi, Asghar Asgari,
Volume 16, Issue 1 (1-2022)
Abstract
In this article, the temperature behavior of output power of superluminescent light-emitting diode (SLED) by considering the effect of non-radiative recombination coefficient, non-radiative spontaneous emission coefficient and Auger recombination coefficients has been investigated. For this aim, GaN pyramidal quantum dots were used as the active region. The numerical method has been used to solve three-dimensional Schrodinger equations and traveling-wave equations. The spectral width of the gain spectrum in each case has been investigated. Eliminating the non-radiative recombination, non-radiative spontaneous emission coefficient and Auger recombination coefficients increased the output power of SLED and in some cases reduced the negative effect of temperature increase on output power.
Fatima Matroodi, Ali Ahmadi, Morteza Zargar Shoushtari, Humberto Cabrera,
Volume 16, Issue 1 (1-2022)
Abstract
Ti-doped tungsten disulfide (WS2) nanosheet-semiconductor is studied for thermo- optical and electronic properties. Thermal diffusivity (D) thermal conductivity (κ) and absorbance were determined as a function of Ti- dopant (0, 7, 14, and 28%). The research focused on the effect of different Ti-dopant concentrations, and we tried to evaluate the thermal parameters using photohermal lens technique as a simple, non-contacting method. The results show an increase in the values of D by 5 times with an increment of Ti-dopant from 0% to 28%. The addition of Ti did not produce any additional phase in the material, although, the separation of the crystallographic planes reduced, indicating the presence of the Ti atoms in the crystal structure.
Hanie Yazdanfar , Seyedeh Mehri Hamidi, Neda Roostaei, Younes Mazhdi, Asieh Soheilian,
Volume 16, Issue 1 (1-2022)
Abstract
ta charset="UTF-8" >Color vision deficiency (CVD) is a disorder in which patients cannot distinguish specific colors. In the last few decades, the researchers have attempted to find a solution to cure this deficiency, despite valuable attempts by scientists, a promising and effective remedy has not been attained yet. As curing of CVD with the tinted or dyed glasses and lenses in colorblind patients is not satisfying, in this work, we have studied a novel and simple method using plasmonic gold nanoparticles in the contact lenses to improve CVD based on surface plasmon resonance of gold nanoparticles in the visible spectral range. In this technique, the dispersion of gold particles into the contact lens and transforming them to plasmonic gold nanoparticles provides a color filter that can be applied in the correction of the red-green type of colorblindness.The modified lens blocks a narrow band centered at 560nm, the wavelength that vision spectra of CVD patients overlap at those ones.
Sarang Medhekar, Puja Sharma, Man Mohan Gupta, Nilaksha Ghosh,
Volume 16, Issue 2 (7-2022)
Abstract
In this paper, a structure is proposed using ring resonator created on 2D photonic crystal (PC) that acts as an add-drop filter (ADF) in all-optical communication systems. The same structure can also act as refractive index (RI) and temperature sensor. The structure is made up of a hexagonal lattice of air holes in a dielectric slab of silicon with the refractive index of 3.46. The band diagram of the considered structure is obtained using plane wave expansion (PWE) method, and optical propagation through it is simulated using finite difference time domain (FDTD) method. The computational analysis is performed on different structural and physical parameters. Transmission efficiency, quality factor and bandwidth are investigated by varying (i) lattice constant (ii) radius of holes of different parts of the structure and (iii) refractive index of different parts of the structure. The chosen parameters result in operating wavelength around 1550 nm. The designed ADF has a footprint of only 68µm2 and a dropping efficiency of 100%. The sensitivity of the structure is determined by determining shifts in the resonance wavelength as a function of the RI of the holes/slab. The designed structure exhibits desirable features like (i) narrow bandwidth of 1.5 nm, (ii) high-quality factor of 1033, (iii) low detection limit of 3.6´10-4 RIU, (iv) high RI sensitivity of 407 nm/RIU, and (v) high temperature sensitivity of 104 pm/K.
Neda Roostaei, Seyedeh Mehri Hamidi, Saeed Javadi,
Volume 17, Issue 1 (1-2023)
Abstract
In this work, a two-dimensional square periodic array was successfully transferred onto a rigid glass substrate during an innovative and simple-design two-step process of pattern transferring using Kapton tape and plasma technology. Flexible and stretchable, Kapton tape was selected for pattern transferring onto the glass for the first time herein; in parallel, the vacuum plasma treatment was utilized to improve surface adhesion properties and aid the pattern transferring process. The proposed 2D square plasmonic array supported the plasmon-induced transparency (PIT) phenomenon, which is caused by the excitation of surface plasmon resonances. The current study simulated the fabricated plasmonic structure using the finite-difference time-domain (FDTD) method and investigated the propagation of surface plasmon polariton (SPP) and cavity modes which enhanced transmission. This fabrication technique can offer new insights for micro/nanofabrication technology.
Sarah Bolandnazar, Samad Roshan Entezar,
Volume 17, Issue 1 (1-2023)
Abstract
In this article, we provide a theoretical investigation into the reshaping of flat-top pulses in a one-dimensional, homogeneous, isotropic, finite-size photonic crystal with two defect layers. We use Fourier transform to find frequency and time spectra, and transfer matrix to determine transmission spectra to find the average duration and power of the output pulse. The pulses with a carrier frequency near the defect mode center and a wide frequency spectrum, undergo the most significant reshaping. Reshaping is strongest for narrow pulses with a carrier frequency at defect mode peaks. The maximum power and duration of the output pulse of a spectrally narrow pulse are all proportional to the pulse duration and exhibit extremes at the frequencies of the defect mode peaks. The power and average duration of a spectrally wide pulse's output pulse are not affected by the carrier frequency.
Neda Roostaei, Seyedeh Mehri Hamidi,
Volume 17, Issue 2 (6-2023)
Abstract
Color vision deficiency (CVD), or color blindness, is a prevalent ocular disorder that hinders the recognition of different colors, affecting many people worldwide (8−10% of males and 0.4−0.5% of females). Recently, there has been a significant focus on plasmonic nanostructures as an alternative to chemical dyes for managing color blindness due to their remarkable characteristics and the tunability of plasmonic resonances. In this work, the plasmonic glasses based on silver nanoparticles with a TiO2 thin layer coating were fabricated using the sputtering technique and proposed for blue-yellow (tritanopia) CVD management. The proposed plasmonic glasses based on silver nanoparticles are more selective than commercial Enchroma glasses because of the tunability of plasmonic properties of silver nanoparticles by controlling their morphology, which provides insights for applications of color vision deficiency improvement. Also, the antibacterial activity of the proposed plasmonic glasses based on silver nanoparticles was investigated against E. coli and S. aureus bacteria, which have exhibited effective antibacterial properties. The results indicate that the silver nanoparticle-based glasses not only aid in tritanopia management but also offer potential for antibacterial applications such as implant coatings.
